Radio communications are now widely used, including on moving vehicles or in any busy situations. Hands-free systems are used for such kinds of radio communications to assure traffic safety or any kind of conveniences. A hands-free system is formed by a radio apparatus, e.g., a cellular phone, and a hands-free apparatus.
A radio apparatus and a hands-free apparatus are linked to each other by a local radio link to form a hands-free system, provided that they are capable of sending and receiving radio signals through the link. Examples of such a local radio link are Bluetooth (TM) and a wireless local area network (WLAN), and particularly in the Bluetooth specifications there is provided a standardized hands-free profile to support such kinds of applications.
Here is assumed a hands-free system formed by a radio apparatus and a hands-free apparatus. The hands-free apparatus has a microphone, a loud speaker, and an operation panel. The hands-free apparatus is connectable to the radio apparatus by a local radio link, and the radio apparatus may be set normal, i.e., to be used while being held by a human hand, or hands-free. When the radio apparatus is set hands-free, a control channel is established on the local radio link.
The radio apparatus is used as an ending node of a communication network. An incoming phone call received at the radio apparatus is transferred to the hands-free apparatus through the control channel. The call may be accepted on the hands-free apparatus, i.e., by operating the operation panel thereof. When the call is accepted on the hands-free apparatus, a voice channel is established on the local radio link to enable a voice communication in a hands-free manner, using the microphone and the loud speaker of the hands-free apparatus.
When a call arrives at the radio apparatus from another ending node of the communication network, i.e., the other party on the phone, the call is transferred from the radio apparatus to the hands-free apparatus through the control channel. If the call is not accepted on the hands-free apparatus during a predetermined time period, the radio apparatus reads out a reply message, like “Sorry, I am not available for the time being”, stored in a built-in memory and sends the reply message to the other party, as one of usual functions of radio apparatuses.
Accepting the call on the hands-free apparatus is usually ineffective after sending the reply message begins. That is inconvenient, in a case where an operation to accept the call has to be delayed due to an instantaneous traffic situation or some other reasons although such an operation has been intended.
Vehicular phone systems were improved to alleviate a danger when a call arrives at a radio apparatus included in the system, and the improved systems are disclosed in the Japanese published patent applications, e.g., H11-4190 and 2003-51896, the English versions of which are available on the Japan Patent Office website.
The former one of those conventional systems determines if the vehicle is moving or not, when a call from another party arrives at the radio apparatus, based on the velocity data obtained by a velocity measurement unit on board. When it is determined that the vehicle is moving, a reply message is sent back, saying that the call cannot be accepted since the vehicle is moving, and a spoken message of the other party is recorded, if any.
The latter one sends a reply message to the other party including vehicular status in addition to the information if it is moving or not at the time when the call arrives at the radio apparatus. That may help not to receive repetitive calls from the other party, who understands the vehicular status well due to the contents of the reply message.
These conventional techniques, however, do not solve the problem that accepting the call on the hands-free apparatus is ineffective after sending a reply message begins.